Nicorandil effect on myocardial perfusion in patients with slow coronary flow phenomenon assessment by gated myocardial perfusion SPECT

Introduction:Patients with the coronary slow flow phenomenon (SCF) frequently experience angina episodes. The purpose of this study was to determine efficacy of nicorandil in myocardial perfusion in patients with SCF. Methods: Twenty patients (50.85 ± 12.96 y) with SCF were studied.  We evaluate coronary slow flow according to protracted thrombolysis in myocardial infarction (TIMI) frame count. After diagnosis of SCF, all patients underwent dipyridamole stress/rest gated 99mTc-sestamibi SPECT. Subsequently, the patients received 10 mg nicorandil BD (20 mg per day). After starting nicorandil for one month, patients underwent dipyridamole stress/rest gated 99mTc-sestamibi SPECT again. Gated SPECT images were analyzed based on 17-segment scoring system, and QPS (quantitative perfusion SPECT) and QGS (quantitative gated SPECT) softwares were used. Results: In patients with SCF subtle perfusion abnormality was noticed. With nicorandil consumption, EDV and ESV were decreased and LVEF was increased in both stress and rest gated SPECT phases (P>0.05). After nicorandil consumption, decreased in most semi-quantitative perfusion indices (Severity score; P=0.03, Extension score; P=0.06, RAW reversibility; P=0.002, severity reversibility; P=0.03 and Extension reversibility; P=0.001) except for RAW score were observed demonstrating significant difference with pre-nicorandil consumption quantities.  In multi-vessels involvement with SCF, there was a trend to see more abnormality with more remarkable post-nicorandil change as compared to the patients with one vessel involvement. Conclusion: The main finding of this study was better myocardial coronary flow after nicorandil consumption in patients with SCF specially those with multi-vessel involvement.